A method of controlling a switch, a terminal and so on (user plane) from an external controller (control plane) is referred to as a CU (C: control plane/U: user plane) separation architecture. A network having a configuration based on the CU separation architecture is referred to as a CU separation network.
As an example of the CU separation network, an OpenFlow network is provided, to which an OpenFlow technique is applied. The OpenFlow technique executes network routing by controlling a switch from a controller. Here, the OpenFlow network is merely one example.
[Explanation of OpenFlow Network]
In the OpenFlow network, a controller like an OFC (OpenFlow Controller) controls behavior of a switch like an OFS (OpenFlow Switch) by operating a flow table of the switch.
The flow table is a table in which an entry is registered, the entry defining a predetermined processing content (action) which should be performed on a packet (communication data) that meets a predetermined matching condition (rule). The packet may be replaced by a frame. A packet group (packet sequence) meeting the rule is referred to as a flow.
The rules of the flow are defined by using various combinations of any or all of a destination address (DA), a source address (SA), a destination port (DP) and a source port (SP) included in a header field of each protocol hierarchical layer of the packet, and can be distinguishable. Here, the above addresses include a MAC address (Media Access Control address) and an IP address (Internet Protocol address). In addition, information of an Ingress port may be available for the rule of the flow.
The action of the flow is usually packet forwarding to a predetermined forwarding destination. Obviously, packet discarding may be specified as the action of the flow.
In the OpenFlow network, usually, when receiving a packet that there is no corresponding entry, a switch transmits an inquiry (entry request) with respect to the packet to a controller. Usually, the switch transmits the packet to the controller as the inquiry with respect to the packet.
In the OpenFlow network, usually, the controller is connected to switches under the controller's administration by a secure channel connection. When receiving the inquiry with respect to the packet from the switch under the controller's administration, the controller calculates a pass of the packet group (flow), and registers an entry of “the packet group (flow) is forwarded to a predetermined forwarding destination” in a flow table of the switch based on the pass. Here, the controller transmits a control message for registering the entry into the flow table to the switch.
The detail of the OpenFlow techniques is described in non patent literatures 1 and 2.